A sample of the organism is currently being contained on floor 3 of site-██. Access to the chamber is permitted only to O5 members only. The sample is contained in a hermetically sealed plastic petri dish, guarded by two level 5 guards.

Description: SCP-XXXX is a parasitic lifeform that absorbs and assimilates prey. The parasite uses the organism to be able to adapt to virtually any environment that can sustain multi-cellular, complex life, which is its principal food and host source. Each individual cell of the creature is both part of a singular multi-cellular lifeform and a distinct, independent entity at the same time. Dual-functionality of the creature enables individual cells and/or collections of cells to function as separate organisms if necessary, which are invariably focused on one goal; assimilating and imitating other lifeforms.

It assimilates other lifeforms by either deploying separate, autonomous parts or using the mass of its own body to capture or seize a host, which will subsequently consume and generate a replica of the host from the biomass of the victim and the parasite itself, which is itself a copy. Depending upon the size or nature of the infectious method, the consumption and replication of a host can take a variable length of time, from a very long time period to a shorter one, depending on whether the assimilating agent are small particles or larger forms. The parasite has the ability to undergo cryogenic stasis, allowing it to lay dormant until discovered by human beings. It's ability to interact with plant based life-forms is largely unknown. When it engages another organism for assimilation, it rapidly generates a haphazard arrangement of limbs and body parts from its own biomass. While seemingly dramatic, this shock-and-awe tactic has proved quite effective as a hunting stratagem. Victims are left stunned by the sudden transformation, allowing the Thing ample time to subdue them. These explosive mutations are generally believed to be comprised of the various anatomies of previously-assimilated species, which are constructed and organized into a formation or set of formations that fit the immediate needs of the parasite. Once a host is captured, the assortment of grasping appendages of the creature penetrate the epidermal layers of victim, it quickly introduces masses of its own cells to begin the process of assimilation. The invading cells immediately capture and absorb all of the victim's cells in their path, and proceed to metabolically break them down as a fuel and energy source for their activities. During this process, the parasite's cells analyze and record the entire genetic code of its victim, which then are subsequently put to use.

Using the newly acquired biomass and genetic information, the creature uses the combined biomass of itself and the host to generate a copy of the parasite that is structured as a complete imitation of the now-deceased and consumed host. Every characteristic and individual quirk of the host is copied, including physiological flaws or health conditions. If circumstances allow, the Thing will remove the clothing of its victims in order to optimize the rate of transformation, because of the fact that during the conversion process, the extremities of the victim will take on an inconsistent, haphazard shape before returning to the form of the host's anatomy. The precise reasons for this are unknown, but it is likely the outcome of the in-progress replica taking in the full genetic record of past victims from its parent organism, in order to perpetuate the parasite's life-cycle. Once the assimilation process is complete, the parent Thing will detach itself from the newly generated replica, which will proceed to enact the same procedure with other lifeforms. Though the full infection procedure has never been witnessed from start to finish, logic suggests that once the process is complete the Thing and its offspring will then resume their respective disguises to pursue their individual or collective goals. If circumstances allow or demand it, either of these replicas can abandon their current forms and take on new configurations to deal with changing situations. If possible, they will continue their subversive activities until they have either collectively or individually subsumed all other potential hosts.

While the effectiveness of this life cycle is prodigious, it does have a number of weaknesses. The first weakness is that while it can assimilate the biomass of any life-form, it cannot account for inorganic and metallic objects, which are quickly ejected from the conjoined mass. This can be witnessed during the events at the Norwegian camp, where metallic objects like piercings, tooth fillings, splints, and pins were discarded from the victim's body, which the remaining camp members used to their advantage to flush out potential replicas. The second weakness would be the biology of the creature itself. While operating as a large, multi-cellular entity, a Thing is difficult to distinguish from those it is imitating, due to the replica's high levels of sentience, but when operating as individual organisms, such as separated appendages, mobile particles, and individual cells, the creature can immediately be exposed. This occurs because in these forms, the Thing has very little if any intelligence relative to a complete replica, and instead operate entirely on the instinctive programs that influence the otherwise sentient behavior of any of these imitations. Because of this, each minute configuration will respond in predictable ways to external and often dangerous stimuli.

Examples of this can be seen in the use of two highly effective methods of detection. The first would be the uninfected blood of any host organism; when in the presence of the cells of the Thing, the blood cells will immediately be captured, assimilated, and imitated by the Thing. Though this has not been witnessed, the Things' fear of this method's effectiveness compelled it to sabotage the efforts of its human foes to use it against the parasite in two known cases. Though the creature can force the biomass of an assimilated host to expand to a maximum size relative to its own fuel and energy reserves, it cannot generate mass that exceeds that limit. In the case of extenuating circumstances that involve combat, the creature is able to not only transform into a combat-capable shape, but is also able to use one or more victims as additional biomass to supplement its own rather than as additional replicas. In this context, the additional material is used by the thing to increase the mass and effectiveness of its new "combat" form, which it will then use against its opponents.

Depending on the circumstances that it finds itself in, the Thing can operate in any fashion it deems suitable. If it is in a situation that requires it to act quickly due to mitigating factors such as short time limits, a limited working knowledge and a large number of rapidly-developing threats, it will react accordingly, employing bold and aggressive maneuvers in order to overwhelm, scatter, and confuse its prey. It will be more inclined to follow this course of action if it knows that there are a large number of potential hosts and opportunities for assimilation. Conversely, if its potential hosts are more likely to be aware of it and have employed defensive measures, the Thing will focus on cunning, stealth, and patience: assimilate in secret, and the use of well-crafted methods of psychological misdirection and physical deception. Though this strategy requires that the creature be patient and avoid open conflict, it is also more dangerous than the former, due to the fact that the thing is more likely to be vulnerable when discovered, but conversely provides greater chances of survival, especially if it has created multiple replicas to serve as decoys.

If attacked with fire or powerful electric shock, it will attempt to attack, escape or play possum. If incapacitated it appears to try to overwhelm its attackers no matter how outnumbered with a violently horrific display of its metamorphic ability, mutating seemingly uncontrollably to the point sentient creatures will flee in terror. Explosives have also been deployed to destroy the creatures form but the lasting effect, other than to render the soft tissues to a spray of blood and pulp, is unknown. Each cell or group of cells is self-aware and has an in-built desire for self-preservation, even at the expense of the larger biomass it spawned from. After the torso of an assimilated individual has burned to death, the head separated away from the fire and developed arthropod-esque legs and eyes stalks to facilitate escape. When a small sample of Thing blood was exposed to a heated wire, in the presence of its form and still infected host, it leaped away in an attempt to escape. Similarly spilled Thing blood was seen to pool and run in rivulets looking for escape.